D/A Converter : Sm5871An (Ic14) - Kenwood DP-M993 Service Manual

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CIRCUIT DESCRIPTION
5. D/A Converter : SIM5871AN (IC14)
Outline
This LSI is a LA-type 2-channel D/A converter
(ZDECO) which has a built-in over-sampling digital filter
and is used for playback of 16 bit digital audio signals.
This LSI also has de-emphasis filters for 3-types of fs
and soft mute function.
Furthermore, the CD player can be set to the normal or
double-speed playback mode without changing the
system clock. Since the package is a 28 pin shrink DIP,
this LSI has high cost performance.
Features
• 2-channel processing
• Serial data input
Complementary number of 2, 16bit/MSB first
* De-emphasis filter (IIS type) : Matched to 3 fs's
• Soft mute
• 32-time (32fs) over-sampling
445 FIR-type filter (45 degrees +9 degrees) employed
Total characteristics after 32fs : attenuation of 40dB,
ripple of band pass of 0.15dB
At double-speed : 16-time (16fs) over-sampling
• XA-type D/A converter (ZDECO)
32fs over-sampling operation (At double-speed :
16fs)
Zero-shift noise shaper of third degree (ZSNS)
Semi-symmegrical PWM output (11 levels : differen-
tial PWM)
e Setting of CD to normal/double-speed playback
mode (DS terminal)
5-2. Block diagram
DIN LRCI
BCKI Q infinity zero [|
MS sensing id
DFS1 У
SCH SE = —.
MUTEO Q
DS
RSTN у
PWM data
generation
block
АМрр1 Q
Ё input interface "e
ttenuation calculation
Noise shaper
calculation
* System clock
(Normal mode) DS=L : 384fs- - -16.9344MHz
@ fs=44.1kHz
(Double-speed mode) DS=L : 192fs- - -16.9344MHz
@fs=88.2kHz
* Built-in quartz oscillation circuit'
* 5V (standard) single power source (normal mode/
double-speed mode)
* Can operate at low voltage (3.2V) (only in normal
mode)
5-1. Pin connection
XTI
ХМрр
AVpp4
RO
BiSW
RON
АМррз
АУрр2
LON
AVss1
LO
АМро1
DVpp
DVss
O
2
3
4
5
6
7
8
9
Filter calculation &
block
(9 AVDD4
21